REALLY?; The Claim: Air-conditioning can cause colds.

By ANAHAD O'CONNOR

Published: July 26, 2011

THE FACTS

In the midst of a nasty heat wave, air-conditioning can make life so much easier to bear. But some people believe that sudden drops in temperature can play havoc with the immune system. Others say air-conditioners act as germ-spewing machines, cultivating bacteria and viruses like petri dishes and then blasting and recirculating them in enclosed spaces.

As with colds and other respiratory ailments contracted in the wintertime, cold air itself is not the culprit - viruses are, said Dr. Ujwala Kaza, an allergist and immunologist at New York University Langone Medical Center.

Still, researchers at Cardiff University in Wales say it's possible air-conditioners may contribute in some small way to respiratory infection. They extract moisture from the air, which can dry out the protective mucus that lines the nostrils, allowing viruses a better chance to become established in the nose.

One study in 2004 compared 920 adult women and found that those who worked in offices with central air-conditioning had higher rates of absence due to sickness and more visits to ear, nose and throat doctors than those without it. A similar study of almost 800 office workers in 1998 also found more symptoms of sickness in workers in air-conditioned offices, compared with workers in offices with natural ventilation.

THE BOTTOM LINE

There is evidence that air-conditioned environments may contribute to colds, but it's not definitive.

This is a more complete version of the story than the one that appeared in print.